1. Field of the Invention
The present invention relates to surface finishing tools and, more particularly, to a rotary power tool for refinishing the surface of metal stamping dies.
2. Discussion of the Related Art
Metal mold presses are used to stamp flat sheet metal into various desired shapes. For example, the automobile assembly operation uses metal mold presses to form automobile body parts. Metal mold presses include one or more stamping dies which are made of metal and have a predetermined shape to impart a desired shape to the sheet metal. The surfaces of the stamping dies are often chrome-plated such that they are quite hard. However, over time stamping dies can crack or dent, which causes the sheet metal stamped by the dies to have a corresponding flaw. Thus, the stamping dies must be repaired or replaced. Repairing the stamping dies is the preferred remedy, due to the costs involved.
In an effort to cut costs, some automobile manufacturers have using to use relatively thin sheet metal for their automobile parts. As a result, maintenance of the stamping dies is now even more important, as imperfections will cause readily visible surface irregularities in the formed parts.
One conventional method for repairing these dies is to use a compound oil which fills in the imperfections on the surface of the die. However, in the case of chrome-plated dies, this method is ineffective because the lubricity of chrome is incompatible with compound oil. Thus, such a method has only limited applicability, and is not a long-term solution to the problem in any event.
Another method is to fill in the holes or cracks by welding, and then grind the surface of the dies smooth to restore the original surface contour. The conventional method of doing this is to use a hand grinder or a file to remove the welding material until it is flush with the surrounding die material. It is critical that too much of the welding material is not removed, or else the surface will again be uneven, and the process will have to be repeated. Such a method is extremely tedious, difficult, and time-consuming, especially when done with the naked eye. Even an experienced worker requires a significant amount of time to properly repair a stamping die by this method, causing a depth production while the die is being repaired.
Others have proposed motorized surface abrading machines that include cylindrical cutters, grinders or abraders which are vertically adjustable relative to a work surface in order to control the amount of material removed. For example, see U.S. Pat. Nos. 915,746, 2,069,700, and 2,166,861. While such devices constitute an improvement over the prior art methods mentioned above, they do not provide an adjustable multi-point support capable of reliably controlling the placement of the cutter, grinder, or abrader relative to the work surface.
In particular, the device disclosed in U.S. Pat. No. 2,069,700 to Emmons has significant shortcomings for use in finishing stamping dies which have had a filler such as welding material applied to a crack or dent. For example, the device includes an adjustable stop positioned in front of the rotary cutter, and a roller directly behind the cutter. Thus, as the tool is advanced, the forwardly disposed stop slides over the raised segment defined by the welding material and raises the cutter up off of the work surface, such that the work surface is not properly finished.
Accordingly, it will be apparent that there continues to be a need for a metal mold repair tool for repairing metal stamping dies that includes an adjustable assembly for reliably positioning a finishing member relative to the work surface as the tool is advanced across the work surface. The present invention addresses this need.